1. Field of the Invention
The present invention generally relates to contact spring assemblies, particularly to a contact spring assembly used in an electronic device.
2. Discussion of the Related Art
Contact spring assemblies are commonly used in input devices or control devices, for example, keys of mobile phones and switches of various electronic devices.
Referring to FIG. 1, a typical key assembly 10 using a contact spring 11 is mounted on a printed circuit board 20, which has at least one conductive contact 21. The key assembly 10 includes the contact spring 11, a flexible supporting sheet 12, and a key body 13. Referring to FIG. 2, the contact spring 11 is a strip-shaped metal sheet, and includes a press portion 110, two fixing feet 111, and a conductive connector 115. The press portion 110 is bent to supply elastic force. The two fixing feet 111 are respectively formed on two ends of the press portion 110, so as to fix the press portion 110 onto the printed circuit board 20. The conductive connector 115 is attached to a middle portion of the press portion 110 and faces the conductive contact 21 of the printed circuit board 20. The flexible supporting sheet 12 covers the contact spring 11, with a portion resisting against the press portion 110. The key body 13 is disposed on the flexible supporting sheet 12. When the key body 13 is pressed, the supporting sheet 12 is forced to deform the press portion 110 of the contact spring 11. The conductive connector 115 is moved to contact the conductive contact 21 by the deformation of the press portion 110, thereby creating an electric signal to the printed circuit board 20. When the key body 13 is released, the press portion 110 rebounds from the deformation thereof. The conductive connector 115 is then moved away from the conductive contact 21.
The conductive connector 115 can only be moved along a direction the same as that of the pressure applied onto the key body 13. Thus, the conductive contact 21 of the printed circuit board 20 must be defined under the conductive connector 115 or be covered by the contact spring 11.
Furthermore, the contact spring 11 may be permanently deformed in case of that a relatively high stress is applied to the key body 13, or undergoing repetitively pressure.
Therefore, an improved contact spring assembly is desired in order to overcome the above-described shortcomings.